Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$57.41	7.548%	$61.7433	$61.74	$61.75	$61.70
Purchase #2	$153.70	3.798%	$159.5375	$159.54	$159.55	$159.50
Purchase #3	$172.81	6.785%	$184.5352	$184.54	$184.55	$184.50
Purchase #4	$152.75	7.538%	$164.2643	$164.26	$164.25	$164.30
Purchase #5	$84.42	7.476%	$90.7312	$90.73	$90.75	$90.70
Purchase #6	$157.80	9.380%	$172.6016	$172.60	$172.60	$172.60
Purchase #7	$103.54	3.389%	$107.049	$107.05	$107.05	$107.00
7 purchase totals =	$882.43		$940.4621	$940.46	$940.50	$940.30